1. Field of the Invention
This invention relates to new and useful improvements in electrical test apparatus and more particularly to a test apparatus for testing the continuity of electrical connections in a rack for supporting circuit boards in an electrical apparatus having a plurality of separate printed circuit board modules.
2. Description of the Prior Art
In recent years, electronic equipment has often been made in the form of a plurality of printed circuit board modules which are supported in slots or other equivalent support in a rack or frame. The circuit board racks have a plurality of pin connectors which fit conductor fingers or the like on the circuit boards which are supported in the rack. The pin connectors are located in card edge connectors at the rear end of the circuit board rack and are therefore often relatively inaccessible for testing. The pin connectors or the like at the rear of the circuit board rack are wired to selected connectors on adjacent circuit board supports to provide the necessary interconnections between selected circuit components on the various racks to provide the complete electrical circuit. The wiring of the connections between the connectors on the slots or supports for the circuit boards is usually done manually and it is necessary to check the connections for continunity to be sure that the proper pin connectors for one board is connected to the proper pin connector for any other board. It is also necessary to check for continunity to determine the possible presence of shorts or of misconnections in the wiring. In the past, it has been necessary to check the wiring of circuit board racks manually using a suitable conductivity meter or signal light and to check the continuity of each separate connector on any given circuit board to the point of connection on the other circuit boards according to the wiring diagram for connecting the various modular circuits.
Buck U.S. Pat. No. 2,951,185 discloses electrical equipment consisting of a chassis or supporting rack having a socket with connectors which receive the connectors on a circuit board module. The chassis is designed to contain a substantial number of separate modular circuits. This apparatus is provided for testing continuity of the circuits on individual circuit boards.
Schmitz U.S. Pat. No. 3,129,991 discloses a printed circuit board rack assembly.
Schaefer U.S. Pat. No. 3,673,397 discloses an electronic circuit tester for testing continunity of circuits on a printed circuit board.
Vinsani U.S. Pat. No. 3,824,462 discloses a test apparatus for testing printed circuit boards.
Berard U.S. Pat. No. 3,953,797 discloses an electronic modular test card which is insertable into a circuit board rack for testing continuity of circuits in circuit boards.
Sullivan U.S. Pat. No. 4,056,773 discloses a test apparatus for detecting open circuits in printed circuit board connectors. The test apparatus includes an array of signal lights (LEDs) for indicating continuity in circuits.
Deegan U.S. Pat. No. 4,087,747 discloses an electronic test apparatus for testing circuit components, circuit assemblies and circuit cards or boards having a plurality of probe contact points.
Wolk U.S. Pat. No. 4,092,593 discloses a circuit board testing machine for positioning one or more test probes relative to a circuit board and wherein the position of the test probes can be automatically positioned and locked in place and in which the circuit board can be replaced in a holder that is substantially moveable against the test probes.
Dice U.S. Pat. No. 4,145,620 discloses a modular-type integrated circuit burn-in apparatus including a plurality of circuit boards and a supporting rack for the boards.